This invention relates to systems and methods for verifying reliability and validity of crowd sourcing users and/or reliability and validity of tasks, executed by crowd sourcing users. Key task implementing procedures are computerized and mapped as system events and/or user actions, which can trigger data obtaining when users navigate in the platforms and/or systems. The obtained data from the triggered data obtaining is authenticated. Stamped data chain is constructed from the obtained data. A reference data chain is used to set the expected geographic location and/or time for task implementing. The reference data chain is generated from the reference information supplied by users. Matching process is implemented by checking if the stamped data chain can match with the preset geographic and/or temporal conditions by the reference data chain. The degree of reliability and validity is determined based on the matching results.